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From: Nick Piggin <npiggin@kernel.dk>
To: Nick Piggin <npiggin@kernel.dk>
Cc: Dave Chinner <david@fromorbit.com>, Nick Piggin <npiggin@suse.de>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/46] Revert "fs: use RCU read side protection in d_validate"
Date: Thu, 9 Dec 2010 16:16:17 +1100	[thread overview]
Message-ID: <20101209051617.GA3436@amd> (raw)
In-Reply-To: <20101209043842.GB3139@amd>

On Thu, Dec 09, 2010 at 03:38:42PM +1100, Nick Piggin wrote:
> > Code changes. It may not be doing what it was originally
> > needed/intended to be doing - I don't need to waste time on code
> > archeology and second guessing when there are others around that can
> > tell me this off the top oftheir head. ;)
> 
> Well the d_validate API is meant to provide that, so it's broken
> whether or not its callers use it correctly. It's also exported
> to external modules...
> 
> Yes we should remove smbfs and rip the cache out of ncpfs and
> remove d_validate entirely when possible (or, provide a more

The reason why I don't remove the caching crap entirely is because
it is not a trivial change to properly remove it, and I don't have
the time or inclination to do it properly and have it tested when
it's easy to provide a correct, simple, and back compatible API.

The patch Christoph posted for smbfs and ncpfs just hacks out where the
dentry is used from the cache, but leaves a lot of cache infrastructure
there to rot.


> reasonable API and caching library entirely in the dcache code
> that a filesystem might use). But this is the right first step.

For the record, if anyone cares, the sanest and simplest way to do this
would be to store the dentry's hash along with its pointer, and have
interfaces to allocate, destroy, insert, and delete from cache, and
lookup based on a supplied compare function. (but obviously we shouldn't
bother unless some good numbers turn up)


  reply	other threads:[~2010-12-09  5:16 UTC|newest]

Thread overview: 105+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-27 10:15 [PATCH 00/46] rcu-walk and dcache scaling Nick Piggin
2010-11-27  9:44 ` [PATCH 02/46] fs: d_validate fixes Nick Piggin
2010-12-08  1:53   ` Dave Chinner
2010-12-08  6:59     ` Nick Piggin
2010-12-09  0:50       ` Dave Chinner
2010-12-09  0:50         ` Dave Chinner
2010-12-09  4:50         ` Nick Piggin
2010-12-09  4:50           ` Nick Piggin
2010-11-27  9:44 ` [PATCH 03/46] kernel: kmem_ptr_validate considered harmful Nick Piggin
2010-11-27  9:44 ` [PATCH 04/46] fs: dcache documentation cleanup Nick Piggin
2010-11-27  9:44 ` [PATCH 05/46] fs: change d_delete semantics Nick Piggin
2010-11-27  9:44 ` [PATCH 06/46] cifs: dont overwrite dentry name in d_revalidate Nick Piggin
2010-11-27  9:44 ` [PATCH 07/46] jfs: " Nick Piggin
2010-11-27  9:44 ` [PATCH 08/46] fs: change d_compare for rcu-walk Nick Piggin
2010-11-27  9:44 ` [PATCH 09/46] fs: change d_hash " Nick Piggin
2010-11-27  9:44 ` [PATCH 10/46] hostfs: simplify locking Nick Piggin
2010-11-27  9:44 ` [PATCH 11/46] fs: dcache scale hash Nick Piggin
2010-12-09  6:09   ` Dave Chinner
2010-12-09  6:28     ` Nick Piggin
2010-12-09  8:17       ` Dave Chinner
2010-12-09 12:53         ` Nick Piggin
2010-12-09 23:42           ` Dave Chinner
2010-12-10  2:35             ` Nick Piggin
2010-12-10  9:01               ` Dave Chinner
2010-12-13  4:48                 ` Nick Piggin
2010-12-13  5:05                 ` Nick Piggin
2010-11-27  9:44 ` [PATCH 12/46] fs: dcache scale lru Nick Piggin
2010-12-09  7:22   ` Dave Chinner
2010-12-09 12:34     ` Nick Piggin
2010-11-27  9:44 ` [PATCH 13/46] fs: dcache scale dentry refcount Nick Piggin
2010-11-27  9:44 ` [PATCH 14/46] fs: dcache scale d_unhashed Nick Piggin
2010-11-27  9:44 ` [PATCH 15/46] fs: dcache scale subdirs Nick Piggin
2010-11-27  9:44 ` [PATCH 16/46] fs: scale inode alias list Nick Piggin
2010-11-27  9:44 ` [PATCH 17/46] fs: Use rename lock and RCU for multi-step operations Nick Piggin
2011-01-18 22:32   ` Yehuda Sadeh Weinraub
2011-01-18 22:42     ` Nick Piggin
2011-01-19 22:27       ` Yehuda Sadeh Weinraub
2011-01-19 22:32         ` Nick Piggin
2011-01-25 22:10           ` Yehuda Sadeh Weinraub
2011-01-27  5:18             ` Nick Piggin
2011-02-07 18:52               ` Jim Schutt
2011-02-07 21:04                 ` Yehuda Sadeh Weinraub
2011-02-07 21:04                   ` Yehuda Sadeh Weinraub
2011-02-07 21:31                   ` Jim Schutt
2011-02-07 21:35                     ` Gregory Farnum
2011-02-07 22:25                   ` Jim Schutt
2011-02-14 17:57               ` Yehuda Sadeh Weinraub
2010-11-27  9:44 ` [PATCH 18/46] fs: increase d_name lock coverage Nick Piggin
2010-11-27  9:44 ` [PATCH 19/46] fs: dcache remove dcache_lock Nick Piggin
2010-11-27  9:44 ` [PATCH 20/46] fs: dcache avoid starvation in dcache multi-step operations Nick Piggin
2010-11-27  9:44 ` [PATCH 21/46] fs: dcache reduce dput locking Nick Piggin
2010-11-27  9:44 ` [PATCH 22/46] fs: dcache reduce locking in d_alloc Nick Piggin
2010-11-27  9:44 ` [PATCH 23/46] fs: dcache reduce dcache_inode_lock Nick Piggin
2010-11-27  9:44 ` [PATCH 24/46] fs: dcache rationalise dget variants Nick Piggin
2010-11-27  9:44 ` [PATCH 25/46] fs: dcache reduce d_parent locking Nick Piggin
2010-11-27  9:44 ` [PATCH 26/46] fs: dcache reduce prune_one_dentry locking Nick Piggin
2010-11-27  9:44 ` [PATCH 27/46] fs: reduce dcache_inode_lock width in lru scanning Nick Piggin
2010-11-27  9:44 ` [PATCH 28/46] fs: use RCU in shrink_dentry_list to reduce lock nesting Nick Piggin
2010-11-27  9:44 ` [PATCH 29/46] fs: consolidate dentry kill sequence Nick Piggin
2010-11-27  9:45 ` [PATCH 30/46] fs: icache RCU free inodes Nick Piggin
2010-11-27  9:45 ` [PATCH 31/46] fs: avoid inode RCU freeing for pseudo fs Nick Piggin
2010-11-27  9:45 ` [PATCH 32/46] kernel: optimise seqlock Nick Piggin
2010-11-27  9:45 ` [PATCH 33/46] fs: rcu-walk for path lookup Nick Piggin
2010-11-27  9:45 ` [PATCH 34/46] fs: fs_struct use seqlock Nick Piggin
2010-11-27  9:45 ` [PATCH 35/46] fs: dcache remove d_mounted Nick Piggin
2010-11-27  9:45 ` [PATCH 36/46] fs: dcache reduce branches in lookup path Nick Piggin
2010-11-27  9:45 ` [PATCH 37/46] fs: cache optimise dentry and inode for rcu-walk Nick Piggin
2010-11-27  9:45 ` [PATCH 38/46] fs: prefetch inode data in dcache lookup Nick Piggin
2010-11-27  9:45 ` [PATCH 39/46] fs: d_revalidate_rcu for rcu-walk Nick Piggin
2010-11-27  9:45 ` [PATCH 40/46] fs: provide rcu-walk aware permission i_ops Nick Piggin
2010-11-27  9:45 ` [PATCH 41/46] fs: provide simple rcu-walk ACL implementation Nick Piggin
2010-11-27  9:45 ` [PATCH 42/46] kernel: add bl_list Nick Piggin
2010-11-27  9:45 ` [PATCH 43/46] bit_spinlock: add required includes Nick Piggin
2010-11-27  9:45 ` [PATCH 44/46] fs: dcache per-bucket dcache hash locking Nick Piggin
2010-11-27  9:45 ` [PATCH 45/46] fs: dcache per-inode inode alias locking Nick Piggin
2010-11-27  9:45 ` [PATCH 46/46] fs: improve scalability of pseudo filesystems Nick Piggin
2010-11-27  9:56 ` [PATCH 01/46] Revert "fs: use RCU read side protection in d_validate" Nick Piggin
2010-12-08  1:16   ` Dave Chinner
2010-12-08  9:38     ` Nick Piggin
2010-12-09  0:44       ` Dave Chinner
2010-12-09  4:38         ` Nick Piggin
2010-12-09  5:16           ` Nick Piggin [this message]
2010-11-27 15:04 ` [PATCH 00/46] rcu-walk and dcache scaling Anca Emanuel
2010-11-27 15:04   ` Anca Emanuel
2010-11-28  3:28   ` Nick Piggin
2010-11-28  3:28     ` Nick Piggin
2010-11-28  6:24     ` Sedat Dilek
2010-12-01 18:03 ` David Miller
2010-12-03 16:55   ` Nick Piggin
2010-12-07 11:25 ` Dave Chinner
2010-12-07 15:24   ` Nick Piggin
2010-12-07 15:24     ` Nick Piggin
2010-12-07 15:49     ` Peter Zijlstra
2010-12-07 15:59       ` Nick Piggin
2010-12-07 16:23         ` Peter Zijlstra
2010-12-08  3:28     ` Nick Piggin
2010-12-07 21:56 ` Dave Chinner
2010-12-08  1:47   ` Nick Piggin
2010-12-08  3:32     ` Dave Chinner
2010-12-08  4:28       ` Dave Chinner
2010-12-08  7:09         ` Nick Piggin
2010-12-08  7:09           ` Nick Piggin
2010-12-10 20:32           ` Paul E. McKenney
2010-12-12 14:54             ` Paul E. McKenney
2010-12-12 14:54               ` Paul E. McKenney

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